The present invention relates to radar array systems, and more particularly to radar arrays mounted on rotating array platforms.
Arrays such as RF beam scanning arrays and the like are often implemented using large rotating array platforms that revolve the array in the azimuth direction. For example, the platform may rotate so as to slew the array by a predetermined azimuth angle, or to scan the entire range of azimuth angles available to the antenna at a constant angular rate. Traditional approaches to implementing rotating radar array platforms involve the use of a variety of mechanical or electromechanical parts including sliprings for providing array power, and large load-bearing bearings to support the rotating platform. However, these components are subject to significant stress, resulting in mechanical fatigue and ultimately component failure. This of course impacts on the reliability of the platform and overall, on the revolving radar antenna system.
Sliprings are a limiting feature in revolving antenna designs. Commercially available sliprings have limited current transmission capability. This limits the power that can be supplied to a conventional radar array. Future radar arrays may require 1000 amps or more, and may not be adequately supported using sliprings.
Fluid cooling presents another limitation on conventional arrays. Coolant has conventionally been transmitted to radar arrays using a rotary fluid joints, which have a tendency to leak.
An apparatus and method for providing a reliable rotating array that is not subject to such component fatigue is highly desired.
One aspect of the invention is a radar antenna system, comprising a radar array mounted on a first wheel. The first wheel has a circumferential portion adapted to engage at least one path disposed on a platform for revolving the radar array about the platform. An axle is coupled to the first wheel. The wheel rotates about the axle as the radar array revolves around the platform during operation.
Another aspect of the invention is a radar antenna system, comprising a wheel, cone or frustum having an axis. The wheel, cone or frustum has a circumferential portion adapted to engage at least one path disposed on a platform for revolving the radar array about the platform. A radar array is mounted on the wheel, cone or frustum, with the axis normal to a face of the radar array. The wheel, cone or frustum rotates about the axis as the radar array revolves around the platform during operation.
Another aspect of the invention is a method for operating a radar system comprising the steps of revolving a radar array having a front face around a platform, and rotating the radar array about an axis normal to the front face as the radar array revolves.
Another aspect of the invention is a method for operating a radar system comprising the steps of revolving a wheel, cone or frustum housing a radar array around a platform, the radar array having a front face, and rotating the wheel, cone or frustum about an axis normal to the front face, so the wheel, cone or frustum rotates as the wheel, cone or frustum revolves.
Another aspect of the invention is an azimuth drive for a radar array, comprising: a rotatable ring portion rotatably mounted to a platform, a motor that drives the rotatable ring portion to rotate, and at least one bracket portion coupled to the rotatable ring portion. The bracket portion pushes in a tangential direction against an array assembly that includes the radar array, causing the radar array to rotate about an axis normal to the radar array and revolve about the platform.
Another aspect of the invention is a method for controlling an azimuth position of a radar array, comprising the steps of: (a) driving a rotatable ring portion to rotate with respect to a platform; (b) pushing against an array assembly that includes the radar array in a tangential direction using at least one bracket portion coupled to the rotatable ring portion; and (c) causing the radar array to rotate about an axis normal to the radar array and revolve about the platform.